I don't agree. Git can only be trusted as long as everybody is playing fair. Git can neither prevent DoS attacks (pushing thousands of useless commits) or double spending (uhm... code duplication in this analogy???) as long as we're talking about a public repo. The only way to prevent attacks in git is by centralising it (restrict access, forcing a pull request workflow). Referencing earlier data by a pointer on its hash is the only parallel I see between git and blockchains. And that's obviously not what makes blockchains special.

And the harm it has done to both the energy and hardware industries is absolutely horrific.

What's the harm for an industry in selling millions of additional devices at higher prices? The hardware industry LOVES Bitcoin. But I totally agree (and I guess everybody working on blockchains does that, too) that the energy consumption needs to be cut down. Migrating from PoW to PoS or other consensus algorithms that don't rely on computing power must have top priority in blockchain research.

edit: For further clarification - it looks to me as if you think blockchains are a new persistency layer, something one should compare to filesystems, databases, and yes, maybe git. But blockchains are the worst persistency layer, no question about it. Nobody with a sane mind would exchange a persistency layer with a blockchain in an existing app.

What makes blockchains great is the possibility of building apps that were not possible with common persistency layers - decentralised apps, whose functionality are so beneficial that it's okay to base them on the technically worst persistency layer that ever existed, blockchains. (To put it in melodramatic terms.)

Blockchain tech can only be trusted if everyone is playing fair also. There are 51% attacks that have been successful.

Miners are also negatively impacting astronomy and other academic research. The cost and wait time for GPU acquisition definitely is good for hardware vendors, but bad for a broad swath of GPU consumers.

Additionally, Dapps are not really a new thing. BitTorrent, Kazaa, etc., have existed for nearly two decades.

Well, 51% means more than half of the users. That's different to "everyone". Git really needs everyone (100%) to play fair. And while Bittorrent, Kazaa, etc. shared data, Dapps also share logic (code).